Preheat the oven to 350 degrees F. Butter the inside of 2 nine inch cake pans. Line the bottoms with parchment paper and butter that as well. Dust with flour being sure to tap out the excess. Set aside.

In a medium bowl, whisk together the flour, baking powder, baking soda, salt and sugar. Create a well in the center of the dry ingredients. To the well add the yogurt, limoncello, lemon zest, lemon juice, melted butter and eggs. Use a whisk to combine the wet ingredients in the well. Switch to a rubber spatula and fold the dry ingredients in to the wet ingredients being careful not to overmix. Divide the batter evenly in the 2 prepared pans and spread to cover the pan. Bake for 20 – 25 minutes or until light, golden brown and a toothpick inserted in the center comes out clean. Allow to cook for 10 minutes in the pan before inverting onto a wire rack to cool completely.

In a medium bowl, combine the cream cheese, mascarpone, limoncello and powdered sugar. Using a handheld mixer, beat on medium speed, starting on low, until light and fluffy, about 4 minutes.

When the cakes are cooled completely, place one layer of cake on a plate or cake stand. Place 1/4 of the frosting on the cake and spread evenly all the way to the sides using a small offset spatula. Place the other layer of cake on top and press gently. Spoon all the frosting on the top and spread evenly pushing the frosting over the edge and spreading it around the sides. Refrigerate for at least 1 hour before serving. Decorate with thinly sliced lemons if desired. Allow to temper at room temperature for 20 minutes before serving.